Monitor Description
WARNING: This page is about a different car, the 2019 Toyota Highlander, 2018 Toyota Highlander, and 2017 Toyota Highlander. However, it is still accessible from the selected car via links, so may be relevant.
The hybrid vehicle control ECU assembly performs many diagnostic tests to verify proper operation of internal ECU systems. In one of these tests, the hybrid vehicle control ECU assembly performs a self-test. If the hybrid vehicle control ECU assembly detects an internal problem during this self-test, it will conclude that there is an internal malfunction and the hybrid vehicle control ECU assembly will illuminate the MIL and store a DTC.